FIELD OF THE INVENTION
The present invention relates to improvements in and to pumps and, particularly, to side channel pumps characterized by increased efficiency and reduced noise generation. Accordingly, the general objects of the present invention are to provide novel and improved apparatus of such character.
In a conventional prior art side channel pump, an impeller with vanes arranged in a star-shaped manner and with open vane interspaces is closely surrounded by a housing. The housing forms axially, next to the impeller, a side channel which is open towards the impeller and in which the medium to be pumped is conveyed by an exchange of pulses with the impeller. German Patent 739,353 shows a prior art side channel pump design which has gained acceptance for single-stage pumps. In this prior pump both the supply and discharge of the medium take place the same side of the impeller. The supply and discharge spaces are consequently concentrated on one part of the pump. In the known pumps of this type, the side channel is also arranged on that side of the impeller on which the medium is supplied and discharged. This arrangement makes it simpler to guide the medium being pumped, because the inflow and outflow ports are connected directly to the side channel.
In other pump types, in which the supply and discharge of the medium take place on different sides of the impeller, and particularly in the case of multi-stage pumps, the medium being pumped has to flow from the supply side through the impeller to the discharge side (Pohlenz: Pumpen fur Flussigkeiten und Gase, Berlin 1975, page 336, 337).
There has been a long standing desire in the art to improve the efficiency and suction capacity of side channel pumps while simultaneously reducing the noise generated during the operation of such pumps